We explored how a simple retrovirus, Mason-Pfizer monkey virus (M-PMV) to facilitate its replication process, utilizes DHX15, a cellular RNA helicase, typically engaged in RNA processing. Through advanced genetic engineering techniques, we showed that M-PMV recruits DHX15 by mimicking cellular mechanisms, relocating it from the nucleus to the cytoplasm to aid in viral assembly. This interaction is essential for the correct packaging of the viral genome and critical for its infectivity. Our findings offer unique insights into the mechanisms of viral manipulation of host cellular processes, highlighting a sophisticated strategy that viruses employ to leverage cellular machinery for their replication. This study adds valuable knowledge to the understanding of viral-host interactions but also suggests a common evolutionary history between cellular processes and viral mechanisms. This finding opens a unique perspective on the export mechanism of intron-retaining mRNAs in the packaging of viral genetic information and potentially develop ways to stop it.

• Keywords
• DEAH-box RNA helicase, DHX15, G-patch, gRNA packaging, retrovirus,
• MeSH
• Cell Nucleus metabolism   virology   MeSH
• DEAD-box RNA Helicases metabolism   genetics   MeSH
• Genome, Viral MeSH
• HEK293 Cells MeSH
• Humans MeSH
• Mason-Pfizer monkey virus * genetics   metabolism   physiology   MeSH
• Virus Replication genetics   physiology   MeSH
• RNA, Viral * metabolism   genetics   MeSH
• RNA Helicases metabolism   genetics   MeSH
• Virus Assembly * genetics   physiology   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• DEAD-box RNA Helicases MeSH
• DHX15 protein, human MeSH Browser
• RNA, Viral * MeSH
• RNA Helicases MeSH

Mason-Pfizer monkey virus (M-PMV), like some other betaretroviruses, encodes a G-patch domain (GPD). This glycine-rich domain, which has been predicted to be an RNA binding module, is invariably localized at the 3' end of the pro gene upstream of the pro-pol ribosomal frameshift sequence of genomic RNAs of betaretroviruses. Following two ribosomal frameshift events and the translation of viral mRNA, the GPD is present in both Gag-Pro and Gag-Pro-Pol polyproteins. During the maturation of the Gag-Pro polyprotein, the GPD transiently remains a C-terminal part of the protease (PR), from which it is then detached by PR itself. The destiny of the Gag-Pro-Pol-encoded GPD remains to be determined. The function of the GPD in the retroviral life cycle is unknown. To elucidate the role of the GPD in the M-PMV replication cycle, alanine-scanning mutational analysis of its most highly conserved residues was performed. A series of individual mutations as well as the deletion of the entire GPD had no effect on M-PMV assembly, polyprotein processing, and RNA incorporation. However, a reduction of the reverse transcriptase (RT) activity, resulting in a drop in M-PMV infectivity, was determined for all GPD mutants. Immunoprecipitation experiments suggested that the GPD is a part of RT and participates in its function. These data indicate that the M-PMV GPD functions as a part of reverse transcriptase rather than protease.

• MeSH
• Cell Line MeSH
• Humans MeSH
• Mason-Pfizer monkey virus chemistry   enzymology   genetics   MeSH
• Polyproteins chemistry   genetics   metabolism   MeSH
• RNA-Directed DNA Polymerase chemistry   genetics   metabolism   MeSH
• Protein Structure, Tertiary MeSH
• Viral Proteins chemistry   genetics   metabolism   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Polyproteins MeSH
• RNA-Directed DNA Polymerase MeSH
• Viral Proteins MeSH

Most retroviruses employ a frameshift mechanism during polyprotein synthesis to balance appropriate ratios of structural proteins and enzymes. To investigate the requirements for individual precursors in retrovirus assembly, we modified the polyprotein repertoire of Mason-Pfizer monkey virus (M-PMV) by mutating the frameshift sites to imitate the polyprotein organization of Rous sarcoma virus (Gag-Pro and Gag-Pro-Pol) or Human immunodeficiency virus (Gag and Gag-Pro-Pol). For the "Rous-like" virus, assembly was impaired with no incorporation of Gag-Pro-Pol into particles and for the "HIV-like" virus an altered morphogenesis was observed. A mutant expressing Gag and Gag-Pro polyproteins and lacking Gag-Pro-Pol assembled intracellular particles at a level similar to the wild-type. Gag-Pro-Pol polyprotein alone neither formed immature particles nor processed the precursor. All the mutants were non-infectious except the "HIV-like", which retained fractional infectivity.

• MeSH
• Simian Acquired Immunodeficiency Syndrome virology   MeSH
• Chlorocebus aethiops MeSH
• COS Cells MeSH
• Gene Products, gag genetics   MeSH
• Gene Products, pol genetics   MeSH
• Humans MeSH
• Mason-Pfizer monkey virus genetics   pathogenicity   MeSH
• RNA, Messenger genetics   MeSH
• Frameshift Mutation MeSH
• Protein Biosynthesis MeSH
• RNA, Viral genetics   MeSH
• Transfection MeSH
• Virion genetics   pathogenicity   MeSH
• Viral Proteins genetics   MeSH
• Rous sarcoma virus genetics   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Research Support, N.I.H., Extramural MeSH
• Names of Substances
• Gene Products, gag MeSH
• Gene Products, pol MeSH
• RNA, Messenger MeSH
• RNA, Viral MeSH
• Viral Proteins MeSH